This invention relates to a combination of an engine block heater and an electrical connector thereto.
An engine block heater generally comprises a mounting member engagable with the engine block for mounting therein and a heating element mounted on the mounting member so as to project rearwardly therefrom into the engine block for heating of the engine block. Various different designs and shapes of the mounting member are provided and the heating element similarly can be shaped and arranged in a number of different shapes to accommodate different designs of engine block and to accommodate different amounts of spacing behind the engine block wall for the heating element to project into the water jacket.
In some cases the mounting member includes a male screw thread for threadedly fastening into a female screw thread into the engine block wall. In other cases the mounting member can be held in place by a clamping arrangement actuated by a screw externally of the mounting member.
In addition, of course, it is necessary to provide an electrical connector for supplying electrical power to the heating element. Generally the electrical connector includes a wire and a connector body which engages with a receptacle on the mounting member. Usually the receptacle comprises a sleeve with a base of the sleeve on the mounting member and an open end of the sleeve facing away from the mounting member. Within the sleeve is provided a pair of pins extending axially of the sleeve. The connector body has a generally cylindrical portion which fits into the sleeve with a pair of bores each for receiving a respective one of the pins so that the connector body is a friction fit within the receptacle to hold the connector body in place. In many engine and block heater constructions, this friction fit between the connector body and the receptacle body is sufficient to hold the electrical connector in place and no additional coupling is necessary.
In some more specialized arrangements, however, it is necessary to provide a separate fail safe holding device which engages a suitable element on the connector and holds this against or onto the receptacle. Up till now the most effective way to provide such a holding device is simply to provide a female threaded collar which slides over the electrical connector and engage a radially extending rib on the electrical connector and is threadedly fastened onto a male screw thread on the outside surface of the sleeve. From a mechanical point of view, this arrangement of the threaded collar is entirely satisfactory and has been used for many years.
However it has been determined that it is undesirable to use a threaded collar as the holding device since the threaded collar can be only applied in assembly of the engine and engine block heater by manual operation of the collar in which the worker rotates the collar a requisite number of turns to effect inter engagement of the screw threads. This operation of rotating the collar requires a significant period of time, but more importantly opens the worker to the risk of carpal tunnel syndrome.
In view of this difficulty, it is one object of the present invention, to provide an improved holding device for holding the connector body onto the coupling member which avoids the necessity for repeated rotation of the holding member in engagement of a screw thread arrangement.